A group of more than a dozen moderate Republicans, including four former Environmental Protection Agency administrators, urged President Obama in a letter Wednesday to set tough new standards to curb carbon emissions from cars and light trucks.

U.S. average fuel-economy improvement of 6 percent a year is “achievable and cost- effective” for U.S. automakers, former Republican U.S. Environmental Protection Agency administrators, governors and members of Congress said in a letter to President Barack Obama, according to a Bloomberg News report.

In a normal world, Republicans would look at Mitt Romney, who is announcing his second run for their party’s presidential nomination today, as a sterling example of one of their party’s greatest success stories since the Reagan era. Unfortunately, it’s that very success that his party seems to have willfully forgotten—and the thing that’s most likely to doom Romney’s candidacy.